DE2546956A1 - PROCESS FOR MANUFACTURING FABRICS WITH DURABLE DEFINITION - Google Patents

Description

The invention relates to a method for producing
Fabrics containing cellulose fibers with permanent dimensional stability and in particular a process that uses formaldehyde
and employing a non-gaseous catalyst to impart wrinkle resistance to fabrics containing cellulosic fibers
to lend.

In recent years there has been a large number of procedures for
Treatment of products containing cellulose fibers, such as
For example, clothing made from cotton or cotton blends with formaldehyde has been proposed in order to bring about permanent crosslinking of the cellulose molecules and thereby give the goods permanent crease resistance and good drying properties. However, problems have arisen and, although a number of the processes have been carried out commercially, there is a great need for improvement.

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serungen. One problem that has become of critical concern in recent times is the amount of chemicals and the energy expended to achieve the desired degree of permanent wrinkles or crease resistance in the tissue. Such economic considerations secure the commercial one The success of any process of this type that uses fewer chemicals and less energy, to provide fabrics with acceptable crease and wrinkle resistance qualities.

As stated in US Pat. No. 3,706,526, the prior art methods lacked reproducibility because control of the formaldehyde crosslinking reaction was difficult. The method of this patent is intended to solve this problem of control by controlling the moisture content present in the cellulosic material during the reaction. The cellulose material is conditioned to give it a moisture content between about k and 20%, preferably 5 to 12%, based on the dry weight of the cellulose fiber, and is then placed in a gas atmosphere that contains water vapor, a cellulose-crosslinking amount of formaldehyde ( e.g. 15 to 60 percent by volume) and contains a catalytic amount of sulfur dioxide. Humidity control is difficult, however, and the use of a toxic gas as a catalyst is a safety factor as well as an additional cost for environmental protection because trickle towers or scrubbers and the like are required to eliminate the toxic substance from exhaust gas or sewage. The presence of the gaseous catalyst and the steam also leads to corrosion in the curing chamber.

CA-PS 897 363 discloses a method of hardening formaldehyde of cellulose fibers, in which a solution of zinc chloride, ammonium chloride, phosphorus

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acid or zinc nitrate, the fabric is conditioned to a moisture content between about 7 and 15 ⁰ A, based on the dry weight of the fabric, and then the fabric containing the catalyst or the product made from it is a formaldehyde or formaldehyde vapor atmosphere (5 to 75 percent by volume ) is exposed at a temperature between about 90 and 150 C. The process requires precise moisture control and is intended to be limited to the use of these select few catalysts.

The use of methanesulfonic acid as a catalyst in the durable press treatment of cotton using relatively large amounts of a plastic-like substance such as dimethylol methyl carbamate (DMMC) as a hardener is also known. Reinhart et al. "Durable-Press Treatments of Cotton" state in the Textile Research Journal "Volume k" 5 $ No. 9 "September 1973 that methanesulfonic acid has proven to be a strong catalyst for permanent form treatments, whereby" its behavior is similar to that of hydroxymethanesulfonic acid, except that it appears to be more stable. However, a relatively large amount of 10 to 15 % of the plastic-like or resinous material DMMC is required. Temperatures of about 121 to about 160 C (25O to about 320 F) are believed to produce about the same results. Because of the large amounts of DMMC and the high temperatures required, this process cannot be considered a viable alternative to a formaldehyde vapor treatment process employing a low concentration of formaldehyde and a low temperature. Therefore, there is a need for a simple and economical method of making permanent wrinkles that does not depend on precise humidity control to moderate crosslinking, does not require high levels of formaldehyde and high temperatures, or uses a noxious gaseous catalyst or other expensive chemicals.

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As in DT-PS (patent application P 25 30 O38.3)

It has been found that the crosslinking of cellulose fibers with formaldehyde vapors proceeds extremely easily when the fibers are in a state swollen by moisture. This is achieved by introducing the fibers into a formaldehyde vapor treatment chamber with a moisture content of more than 20 percent by weight, preferably more than 60 percent by weight, based on the dry weight of the fibers. Under these conditions, it has been found that the concentration of formaldehyde in the steaming chamber and the amount of formaldehyde added can be kept to a minimum and the reaction can be controlled by impregnating the cellulosic material with the amount of a selected non-gaseous catalyst which will produce the desired degree of crosslinking among the applied curing conditions. It has now been found that if the non-gaseous catalyst is sulfuric acid or an alkylsulfonic acid, such as methanesulfonic acid, ethanesulfonic acid or the like, even lower concentrations of formaldehyde can be used. Even more surprising is the fact that the reaction temperature is so much lower than in the above invention, which gives the present process great commercial importance.

The invention is therefore intended to provide an improved method for producing permanent wrinkles, in which the formaldehyde concentration in the steam treatment chamber can be kept at a low value, whereby not only the risk of explosion and fire, but also the costs are considerably reduced; a process that enables precise control of the catalyst present and avoids the restriction to the use of water as a reaction moderator, a

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drive, in which the presence of formaldehyde gas in the curing chamber in the presence of a gaseous catalyst and moisture, which leads to the formation of lower formaldehyde polymers, the incrustations on the the device used to carry out the method is avoided; and finally the invention aims to a continuous Vorhärtpreßverfahren lead to the production of wrinkle-free fabrics.

The method according to the invention of the type mentioned at the beginning generally comprises the impregnation of a cellulose fiber containing tissue with an aqueous solution containing a certain amount of sulfuric acid or an alkyl sulfonic acid, such as methanesulfonic acid, ethanesulfonic acid or the like, which is able to catalyze the crosslinking reaction between formaldehyde and cellulose, then that Contacting the impregnated fabric with a moisture content of the fabric of over 20 percent by weight and with practically -completely swollen fibers with formaldehyde vapors and finally hardening to improve wrinkle resistance of the fabric · The fabric impregnated with the catalyst is preferably immediately treated with formaldehyde vapors in this process treated.

The invention relates in detail to a method of the type mentioned at the outset, which is characterized in that a tissue containing cellulose fibers is treated with an aqueous sulfuric acid or alkylsulfonic acid solution capable of catalyzing the crosslinking reaction between formaldehyde and cellulose to form an impregnation of 0.1 to about 0.5 % of the catalyst impregnated in the fabric on a dry weight basis, then the impregnated fabric with a moisture content of about 20% by weight or above with the in practically complete

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cellulose fibers in the swollen state are exposed to formaldehyde vapors and cured under conditions in which formaldehyde reacts with cellulose in the presence of the catalyst to improve the crease resistance of the fabric.

The invention uses unlimited amounts of moisture to control the crosslinking reaction, since the crosslinking reaction is in the highest possible swelling state of the cellulose fiber is extremely effective. The relatively large amount of water that is present allows the formaldehyde to be converted more effectively into the hydrate, which is the crosslinker · So can optimal results can be achieved with much less formaldehyde.

During the crosslinking reaction in the curing stage, moisture is given off by the fabric as the crosslinking progresses, which leads to a decrease in the moisture content in the fabric. In fabrics with a moisture content of 20 % or less, this tends to decrease the effectiveness of the crosslinking reaction, requiring higher concentrations of formaldehyde. In the method according to the invention, moisture is given off starting from a high value, that is to say more than 20 %, preferably more than 30 % _t, for example between 60 and 100 % or more, and the crosslinking is optimized. Moisture, which is so difficult to control, is not a problem with the invention, which only requires the moisture content to be above 20 % , which is easy to ensure. Of course, water must not be present in such an excess to allow the catalyst to migrate on the fabric.

The necessary moisture can be supplied to the fabric by any conventional method.It can be added separately or in the form of an aqueous solution of the catalyst

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for example by padding, misting, spraying or the like. A spray leads to one in a very short time high moisture content. In addition, a water spray ensures uniform humidification.

In the process according to the invention, the amount of catalyst used controls the crosslinking. Since the catalyst can be applied to the fabric in the weaving mill using conventional methods that lead to an even application, precise control of the catalyst is ensured. An aqueous solution of the catalyst is preferably padded onto the fabric in order to supply both the catalyst and the moisture in one operation. Of course, a spray technique could also be used. Because the catalyst is not gaseous, it is not subject to diffusion, air currents, the humidity of the garment in the chamber, or the concentration of vapor within the chamber, and is easier to control and manipulate.

The amount of catalyst can vary depending on the particular type of fabric being treated and the properties desired of the finished fabric. In general, however, the catalyst is used in the fabric in an amount on a dry weight basis in the range from 0.1 to about 0.5%, preferred about 0.125 to 0.4%. It will be particularly appreciated that these levels are a substantial reduction that used in a formaldehyde vapor treatment process Represent catalyst quantities.

The catalyst can be applied to the fabric from an aqueous solution using conventional techniques, preferably by padding or spraying. Preferably, the fabric is continuously pre-cured by first applying the aqueous

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Catalyst solution is applied to the fabric, moisture is added if necessary and formaldehyde vapors are then applied to the fabric exposed, cured and then washed to remove excess catalyst.

The concentration of the catalyst solution can be such that the amount of water is added with the catalyst, which is necessary in order to completely swell the cellulose fibers without further addition of moisture. In this In this case, the treatment with formaldehyde vapors usually takes place immediately after the catalyst is applied to the fabric was brought. Only two process steps can be possible, the application of the catalyst solution and the treatment with formaldehyde vapors at the appropriate curing temperature. Of course, the fabric can first become an item of clothing processed and then impregnated with an aqueous solution of the acidic catalyst, whereupon with formaldehyde vapors is treated.

The following examples show the effect of the moisture content of the treated fabric on the wrinkle resistance of the washed product:

example 1

The following samples of a printed 80 × 8θ cotton fabric were padded with aqueous solutions of methanesulfonic acid up to 100% in order to provide the amount of catalyst indicated in Table I. The samples were then sealed in a reactor having a volume of about 3 ^ 0 1 (12 cubic feet) at room temperature and exposed to formaldehyde vapors released from paraformaldehyde over a period of 4 minutes. Then the temperature in the reactor was increased to 93 C (200 ⁰ F) and the sample was removed. That was the test

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washed and drum dried before testing. The wrinkle resistance (Wrinkle recovery) was determined by the A.A.T.C.C. test method 66-1968 and detergency (D.P. laundry) determined according to A.A.T.C.C. test method 124-1969, wherein a rating of 5 is extremely satisfactory.

Table I.

Catalyzed with methanesilfonic acid, crosslinked with formaldehyde rehearse

sample
No. Kataly
sator % Curing tempera- crease-proofxg-
maximum speed
⁰ C ⁰ FWF W + F 200 I6O 159 319 DP laundry,
valuation 1 0.5 93 200 159 161 320 5 2 0.4 93 200 159 160 319 5 3 0.3 93 200 162 161 323 5 4th 0.2 93 200 154 155 309 5 5 0.175 93 200 152 146 298 3 6th 0.150 93 200 l49 148 297 2.8 7th 0.125 93 200 133 130 263 2.5 8th 0.100 93 200 107 113 220 2 9 0.075 93 200 103 110 213 1.5 10 0.050 93 1

As can be seen from Table I, good results are obtained when a catalyst concentration of 0.175 % to 0.2 % is used. Obviously, a catalyst concentration above 0.2% is still effectively catalyzing the system, however deterioration or degradation of the tissue can occur to the same extent as the concentration of the catalyst

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increases · Concentrations of 0.125 % still lead to a considerable treatment, but with a certain loss of washing behavior. Thus the concentration range from 0.175 to 0.2 % is preferred.

As stated in the DT-PS ..... (patent application P 25 30 O38.3) mentioned at the outset, the high moisture content in the fabric leads to the complete swelling of the cellulose fibers and optimizes the crosslinking reaction, which results in improved crease resistance. As a result, considerably less formaldehyde is required than with known vapor phase processes. By using sulfuric acid or an alkyl sulfonic acid, even further reductions in the combined concentration of formaldehyde vapor and catalyst can be achieved. With the method according to the invention using methanesulfonic acid as a catalyst in concentrations of only 0.2%, a complete treatment of the tissue is achieved using a formaldehyde concentration of 1.53 percent by volume. Full treatment means a wrinkle recovery at angles of 309 to 322 °. In general, the formaldehyde concentrations in the treatment chamber are between about 1.0 and about 6.5%, preferably about 1.0 and 3% by volume. The dry weight gain due to the reaction of the formaldehyde with the fabric at this concentration is generally less than about 0.5 %. With formaldehyde concentrates below about 1% by volume in the treatment chamber, the washing behavior and the crease resistance are less satisfactory than desired. At concentrations above about 3 % there is usually no significant improvement in these properties.

The inventive method makes it possible to achieve the desired duration fona properties using a minimum

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To achieve amount of formaldehyde and catalyst, which leads to a direct cost reduction of the process.

The use of low concentrations of formaldehyde in the treatment chamber also significantly lowers that of formaldehyde Existing fire hazard, since formaldehyde in concentrations of 7 percent by volume or more in the mixture Air tends to explode.

The curing temperature at which final crosslinking occurs is in the range of about 80 to 100 ° C (175 to 212 ° F). Advantageously they should be at 93 ° C (200 ⁰ F) to ensure that sufficient cross-linking takes place to impart the necessary buckling strength to the tissue. Temperatures above about 107 C (225 F) or more, as conventionally used, do not improve the process of the present invention and only add to the overall cost of the process and can cause excessive degradation or deterioration. The formaldehyde treatment and curing can take place in the same treatment chamber or in separate chambers or zones of the treatment facility.

Occasionally, depending on the desired properties of the fabric, it is desirable to add a polymeric, resinous additive to the fabric that is capable of forming a soft film. Such additives can be, for example, a latex of a fine aqueous dispersion of polyethylene, various alkyl acrylate polymers, acrylonitrile / butadiene copolymers, diacetylated ethylene / ethyl acetate copolymers, polyurethanes and the like.

Such additives are well known in the art and are generally commercially available in concentrated aqueous latex form. For use in the method according to the invention

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such latex is diluted to provide about 1 to 3 % polymer solids in the aqueous catalyst containing pad bath prior to treating the fabric with it. However, it is not necessary or desirable to add monomers or formaldehyde binding agents.

The influence of the curing temperature and the catalyst concentration is illustrated in the following example.

Example 2

The following samples of a printed 80 × 8θ cotton fabric were padded with aqueous solutions of methanesulfonic acid up to 100% absorption in order to give the amount of catalyst given in Table II. The samples were then tightly enclosed in the reactor at room temperature and exposed to formaldehyde vapors which were released from paraformaldehyde over a period of 4 minutes to a maximum concentration of 6 percent by volume. The fabric inside the reactor was then brought to the specified temperature and finally removed.In addition, a commercially available plasticizer (VIVA) was used where indicated.

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Table II

% Tree cataly- max. Temp. C ( ⁰ F) soft crease resistance DP laundry wool sator % metal glazier % WFW + F

fV-i trn i

_m 1 1.0 27-38 (80-100) -0- 84.7 83.7 168.4 1

p 2 0.5 79.4 (175) 78.3 (173) -0- 133.0 i42, O 275.0 1

3 0.5 85.0 (185) 82.2 (l80) -0- 156.7 157.0 313.7 2,

¹ ^ 4 0.5 85.0 (185) 82.2 (180) -0- 159.7 158.0 317.7 3 »

0.5 93.3 (200) 90.6 (195) -0- 159.3 160.7 320.0 4-5 ^

0.5 79.4 (175) 78.3 (173) 2.0 143.7 l42.3 286.0 3

0.5 85.0 (185) 82.2 (180) 2.0 157.3 154.0 311.3 3

0.5 85.0 (185) 82.2 (180) 2.0 166.0 160.3 326.3 4

0.5 93.3 (200) 90.6 (195) 2.0 166.3 164.0 330.3 5

$ 254695

As can be seen from Table II, a temperature of about 38 ⁰ C (100 ⁰ F) is not sufficient to achieve satisfactory permanent shape properties or crease resistance, even with a catalyst concentration of 1 %. To recognize but on the other hand, that a temperature (175 ⁰ F) to about 93 ° C (200 ⁰ F) leading from about 79 ° C to a sufficient reaction. The use of a fabric softener improves the DP washing properties of the fabric.

Example 3

The procedure was as in Example 2, with different catalyst concentrations at different curing temperatures, as indicated in Table III. The catalyst used was methanesulfonic acid, and the tensile strength and tear strength were determined according to standard conventional tests in the art.

As can be seen from Table III, the strength of 100 % cotton is somewhat reduced. However, the invention is applicable not only to pure cotton fabrics, but also to mixtures with strength-increasing materials.

As tissue containing cellulose fibers, which according to the invention Process can be treated, various natural or man-made cellulose fibers and their Mixtures are used, such as cotton, linen, hemp, jute, ramie, sisal, rayon, e.g. regenerated cellulose (both viscose and caprammonium). Other fibers that are blended with one or more of the cellulose fibers mentioned above can be used are e.g. polyamides (e.g. nylons), polyesters, acrylic fibers (e.g. polyacrylonitrile), Polyolefins, polyvinyl chloride and polyvinylidene chloride. Sol-

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Before mixtures contain preferably at least 35 to kO weight percent, particularly preferably at least 50 to 60 weight percent cotton or natural cellulose fibers.

The fabric can be a resin treated material, but is preferably a non-resin treated material; it can be knitted, warp-knitted, woven, unwoven or constructed in a different way. It can be flat, folded, pleated, be lined or edged or molded before it comes into contact with the atmosphere containing the formaldehyde comes. After processing, the molded, wrinkle-resistant fabric retains virtually the life of the product the desired shape. In addition, the product has excellent washing behavior itself repeated washing.

Example 4

The procedure was as in Example 3, with the exception that polyester-cotton blended fabrics were used; the The results are shown in Table IV.

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Table III

Sample Kataly- Hardening- Crinkle Resistance- Tensile- % Tear-Resistance-% DP-Wash-

No. sator % temperature WFW + F speed remained cautious

⁰ C ( ⁰ F) kg lbs kg lb_s

1 0.5 79.4 (175) 114 120 234 - - - _ 2

2 0.5 85.0 (185) 155 153 308 4.536 10 27 0.331 0.73 46 4

3 0.5 93.3 (200) 160 159 319 3.175 7 19 0.154 0.34 22 4

cn 4 0.4 79.4 (175) 93 102 195 - - - 3

σ 5 0.4 85.0 (185) 152 149 301 5.443 12 32 0.181 0.40 25 5

^<Ω 6 0.4 93.3 (200) 159 l6i 320 2.722 6 16 0.168 0.37 23 5

S 7 0.3 79.4 (175) 92 96 188 - _ _ ₂

- » ⁸ 0 * 3 85.0 (185) 138 l4l 280 5.443 12 32 0.240 0.53 34 4

2 9 0.3 93.3 (200) 159 160 319 4.082 9 24 0.181 0.40 25 5

co IO 0.2 79.4 (175) 135 136 271 6.804 15 4l 0.363 0.80 53 4

-3 11 0.2 85.0 (185) 150 149 299 5.443 12 32 0.236 0 52 33 4

κ »12 0.2 93.3 (200) 162 161 323 3.629 8 22 0.213 0.47 30 5

13 Control 91 104 195 16.783 37 - 0.717 1.58 - 1

Table IV

Methanesulfonic acid as a catalyst in the vapor-phase formaldehyde crosslinking of cotton /

Polyester blends

Polyester Art Kataly- Max. Temperature Softma- Wrinkle Resistance
Cotton aator % ⁰ C ( ⁰ F) rather %

Metal glass (Viva)

CJ) 1 286 0.5 0982 2
3 286
T-9 0.3
0.5 1/09 ' 4th
5 T-9
286 0.3 ^ ***
KJ 6th T-9

93.3 (200) 90.6 (195) 2.0

93.3 (200) 90.6 (195) 2.0

93.3 (200) 90.6 (195) 2.0

93.3 (200) 90.6 (195) 2.0

Crease resistance
WF W + F 167.3
160.7 326.6
314.0 DP-Washe 15 9.3
153.3 162.7
150.3 329.0
303.6 5
4-5 166.3
153.3 139.0 258.3 5
4-5 119.3 128.0 253.7 - 125.7

⁺ 'Art 286 (Springs Mills) is a 65/35 polyester-cotton blend.
Art T-9 (Springs Mills) is a 50/50 polyester-cotton blend.

(T) LO CT-

Example 5

Various mixed fabrics, as listed in Table V, were treated with a solution which contained the specified amount of methanesulfonic acid, plasticizer 2.096 (Viva) and 0.1 % wetting agent (Triton X-100).

The fabrics were padded up to 100% uptake, then stretched smooth on a tenter frame and firmly enclosed in the reactor. The specified amount of paraformaldehyde was then released and evaporated over a period of k min to saturate the tissue, whereupon the air in the reactor was brought to 93.3 ° C (200 ° F) and the sample removed (in the case of tissue type 286, which is a heavier fabric, a final temperature of 98.9 ° C (210 ° F) was used).

All samples were washed and drum dried before any physical tests were performed the results of which are given in Table V.

As can easily be seen from Table V, a full treatment at low catalyst and formaldehyde concentrations, the latter e.g. at 1.53 percent by volume will.

Example 6

The procedure was as in Example 5, 20 g of paraformaldehyde and the specified mixed fabrics being used. The results are shown in Table VI. The Aushärt-Endtemper a door was 93.3 ° C (200 ⁰ F).

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Table V

Methanesulfonic acid-catalyzed formaldehyde crosslinking on various mixed fabrics.

sample catalyst Paraform Formalde 5 1.53 5 1.53 5 1.53 5 1.53 Crease resistance F. W + F No. % aldehyde
U) hyd 5 1.53 5 1.53 5 1.53 5 1.53 V tissue
art 429 65/35 polyester-cotton batiste 65/35 polyester-cotton web 65/35 polyester-cotton twill fabric 5 1.53 5 1.53 I63 327 1 o, 3 0.3 0.4 5 1.53 10 3.06 164 16Ο 322 2 0.2 0.2 0.3 10 3.06 10 3.06 162 tissue
art 638 0.2 10 3.06 10 3.06 I6O 319 3 0.1 10 3.06 159 163 323 4th 0.4 10 3.06 160 tissue
art 286 0.3 15th 4.59 I6O 311 5 0.2 5Ο / 5Ο polyester-cotton web 151 159 312 6th 0.1 0.300 153 159 309 7th Oil 0.200 150 147 279 8th 0.175 133 159 311 9 0.300 152 159 312 10 0.200 153 155 306 Ii 0.175 151 145 274 12th 129 145 271 13th 126 Tissue-
art T-9 157 317 14th 160 153 313 15th 157 155 312 16 157 151 306 17th 155 150 300 18th 150 l4l 288 t9 147

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sample

No.

1
2

3
4th

5
6th

Table VI
Methanesulfonic acid catalyzed, formaldehyde crosslinked poly

ester-cotton blend

Mixed catalyst crease resistance
Type sator % WFW + F

65/35
65/35
50/50
50/50

0.5
0.3
0.5
0.3

159
153
166

153

65/35 control 119
5O / 5O control 126

326

163
150

139
128

329
303
258
254

Tensile strength, weft kg (lbs)

31.75 (70) 31.30 (69) 19.5O (43) 20.4l (45) 28.58 (63) 28.58 (63) tensile strength, weft (l bs)

3.01 (6.63) 2.90 (6.40) 0.98 (2.15) 0.91 (2.01) 2.97 (6.54) 0.97 (2.13)

Wear D.P. laundry

! ^ Loss% Remaining Rating ben

13.9

9.7

21.3

12.4

4.1 3.1

86.1 90.3 78.7 87.6

95.9 96.9

4.5

4.5

U

Wear in the accelerator at 2500 rpm for 2 min.

Table VI clearly shows that optimal physical properties are obtained using blended fabrics and low catalyst concentration can be obtained.

CT! J> CD CD

he

Quite unexpectedly, it was surprisingly found that sulfuric acid also effectively catalyzes the formaldehyde crosslinking reaction of cellulose, so that a high degree of crease resistance is achieved without excessive degradation or discoloration, as would have been expected with the use of sulfuric acid. Apparently the low sulfuric acid concentration (ie from 0.1 to 0.4 %) and the required low temperature reduce the decomposition or deterioration of the tissue on the cellulose which normally occurs when sulfuric acid is used to catalyze the formaldehyde crosslinking at higher speeds or is used to catalyze conventional resin systems. This is illustrated by the following example.

Example 7

Samples of a printed 80 × 80 cotton fabric were padded to 100% absorption with an aqueous solution containing the specified sulfuric acid concentration, 2% plasticizer (Viva) and 0.1 % wetting agent (Triton X-IOO). The tissue was then 10 g paraformaldehyde (3.06 volume), evaporated over a period of 4 min, exposed, then 93 j 3 ° C (200 ⁰ F) heated and then washed and tumble dried.

Table VII

Sample sulfuric acid soft crease resistance DP laundry no. % More WF W + F rating

(Viva) %

1 O, 2 2 , 0 159 161 320 4, 5 2 O, 2 2 , 0 162 160 322 5, 5 3 O, 4th 2 , 0 165 164 329 0

These results clearly show that sulfuric acid is as effective as methanesulfonic acid in catalyzing the reaction. The Ver-

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driving is well catalyzed by the acid.

The device necessary to carry out the method is very much simplified, since the humidity control or -control is not used as a moderator for the reaction, the aqueous, acidic catalyst can by padding or spraying can be applied. Moistening the tissue, if additional moistening is required, can be done by adding the tissue is passed through a water mist before it enters the reaction chamber. The fabric containing the latent catalyst can then be placed in a reaction chamber which is filled with gaseous formaldehyde from any suitable source, e.g. a formaldehyde generator in which formaldehyde vapor is generated by heating paraformaldehyde The formaldehyde vapors are diluted with air or another gas to obtain the desired concentration. Preferred the formaldehyde is generated outside the chamber containing the fabric in order to reduce the risk of fire.

The reaction chamber is preferably one which can be heated to a sufficiently high temperature to ensure that the crosslinking reaction takes place. The atmosphere in the reaction chamber is preferably a mixture with 1 to 3 »0 volume percent formaldehyde gas, diluted with air or an inert gas such as nitrogen. Higher concentrations of formaldehyde could be used but are not necessary in this process.

All of the results given above were obtained using the following standard methods:

1. D.P. Wash - A.A.T.C.C. Test Method 124-1969.

2. Wear - Accelerotor Method A.A.T.C.C.

Test method 93-1970 weight loss.

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3 Crease resistance (crease recovery) - recovery method A.A.T.CC. test method 66-1968.

4. Tensile Strength - A.S.T.M.D-1682-64 (Test IC).

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Claims (5)

PATENT CLAIMS 1. A process for the production of tissue containing cellulose fibers with permanent dimensional stability, characterized in that a tissue containing cellulose fibers with an aqueous, capable of catalyzing the crosslinking reaction between formaldehyde and cellulose
Sulfuric acid or alkyl sulfonic acid solution impregnated to form an impregnation of 0.1 to about 0.5 % of the catalyst in the fabric on a dry weight basis, then exposing the impregnated fabric to a moisture content of about 20% by weight or above with the cellulosic fibers in a virtually fully swollen state and curing under conditions in which formaldehyde reacts with cellulose in the presence of the catalyst to improve the wrinkle resistance of the fabric. 2 · A method according to claim 1, characterized in that the catalyst used is Methaneulfonsäure · 3 · The method of claim 1, characterized in that ale catalyst sulfuric acid is used. 4. The method according to one of claims 1 to 3 »characterized in that if the moisture content of the tissue at the time of treatment with foraldehyde is over about 30 percent by weight. 609821/0972 5. The method according to any one of claims 1 to 4, characterized in that cotton is used as the fabric 6. Method according to one of Claims 1 to 4, characterized in that a cotton-polyester mixture is used as the fabric. 7 »A method according to any one of claims 1 to 6, in particular claim 2, characterized in that the catalyst is used in a concentration in the range of about 0.125 to 0.2% and a temperature during the crosslinking reaction below about 1OO ⁰ C (212 ° F ) is applied 8 · Method according to one of claims 1 to 7 «characterized in that the fabric has an atmosphere with a Content of about 1.0 to 3.0 percent by volume of formaldehyde is exposed. 9. The method according to claim 3t, characterized in that the sulfuric acid is used in a concentration of 0.1 to 0.4 % . Process for the production of fabric containing cellulose fibers with permanent dimensional stability, characterized in that a fabric containing cellulose fibers with at least about 60 weight percent water in the fabric, based on the dry weight of the fabric, with an aqueous, about 0.1 to 0.5 weight percent sulfuric acid or methanesulfonic · acid-containing solution impregnated this fabric then while maintaining the Vaesermenge exposed to formaldehyde vapors and at a temperature of about 79.4 to 100 ⁰ C (175-212 F) for the crosslinking reaction between the cellulose and the formaldehyde while d & m swollen state of the fibers to improve the crease resistance of the yarn fabric is hardened 609821/0972